Vacuum Systems

Industrial process operating loads and optimal set points are not usually accurately known at the time of design, so often there is significant mismatch between equipment and the process it serves. To overcome this uncertainty, designers typically oversize equipment. Over time, process changes and equipment efficiencies decline, so equipment might be operating less efficiently than at start-up. Or, equipment can be undersized, thereby hampering the entire system and causing other inefficiencies to compensate. For instance, too much steam usage in the dryer section of a paper machine can occur because of inadequate vacuum at the wet end.

Multiple vacuum pumps can be running mostly “dead-headed” in the many production systems that don’t require constant flow.  Any system that evacuates a small volume and then holds a product down while it is being machined, or sucks a bag shut to seal will spend the majority of its time not moving much mass of air.  This type of operation is found everywhere in secondary wood processing, machining, food packaging, and many other industries.  Anywhere vacuum is used as a motive force or to evacuate a small volume repeatedly.  This article will apply to any of these types of systems- and not apply to constant-flow vacuum applications in the process industries.

ADA Möbelfabrik, headquartered in Anger, Austria, is one of Europe’s largest manufacturers of furniture. Upholstered furniture, beds, mattresses and slatted frames are produced for the Austrian market and for many other European countries in two shifts, using modern manufacturing techniques. The vacuum supply required for securing items to the CNC machining centers is provided via a central vacuum plant produced by Busch. By opting for this vacuum system, ADA has integrated an extremely economical and reliable vacuum supply into the production process.

Vacuum chucks and holding devices have been used in many industries for a variety of purposes, from lifting packages to holding items for machining. With the introduction of CNC routing machine-tools for mass production (of wood furniture, plastics and other non-magnetic materials), there was a need to clamp-down large work pieces on the flat router tables. Mechanical clamping was not an option as it caused damage to the work pieces and didn’t satisfy the need to quickly place items on the table and clamp instantly.

During the summer season, vegetables tend to deteriorate quickly once harvested from the field—or during postharvest stage of the cold chain. In traditional cold chain systems, vegetables are put into a chilled cooler for preservation, a process that requires approximately 12 hours for the product to achieve proper temperature. In some instances, as much as 25 percent of food product in the chilled cooler will decay before arriving at a proper storage area. Fortunately, there is a process for improving the effectiveness of the postharvest stage—vacuum cooling.

Vacuum systems are considered “black magic” by most plant engineers, even more so than compressed air. Terms like icfm, cfm, torr, and Nm3/hr get bandied around and confuse us all. What plant engineers know is what works. If they run vacuum pump X at vacuum level Y, everything works. That is a hard thing to change if there are inefficiencies in the system, even when an audit is recommending change. One of the biggest opportunities I run into for savings is the consolidation of multiple vacuum systems running at a lower absolute pressure (higher vacuum) than is really needed. Therefore, educating the customer is critical.

Two years ago, sales were picking up and we began operating six extrusion lines on most days. We had to bring in some portable chillers, to keep up, and we started looking at buying a larger cooling system. We wanted to get rid of the portable chillers and have room to grow into four more extrusion lines. The new system we looked at was a 100-ton system that would have cost us around $150,000 in capital and installation and with a larger monthly electricity bill.

We were about to buy the new 100-ton chiller when our President, Abe Gaskins said, “Hold-on, can we replace the Liquid Ring pumps with something that doesn’t consume water”? That was our “Eureka!” moment.

Most printing facilities use vacuum for one process or another.  I recently spoke with Jesse Krivolavek, (a vacuum system efficiency specialist with IVS, Inc.) about his recent adventures in the world of printing.